Digital objects are formatted using the Metadata Encoding and Transmission Standard (METS) standard, and should conform to the "Enhanced Service Level" specifications defined in the CDL Guidelines for Digital Objects.

Collection guides and digital objects are assigned persistent identifiers according to a naming scheme called the Archival Resource Key (ARK), to ensure long-term public access. The ARK scheme was developed at the National Library of Medicine and is currently in production use at the CDL.

OAC Search and Delivery Platform: XTF

The repository supports a CDL-developed XML- and XSLT-based delivery platform, packaged as the eXtensible Text Framework (XTF). The XTF system contains Java Servlets and tools that permit users to perform Web-based searching and retrieval of electronic documents. It utilizes Lucene indexing technology and XSLT stylesheets for generating displays.

XTF supports the search and delivery of collections that is user-friendly, flexible, and viable for the long term. XML provides a means by which the structure and meaning of a document can be specified by "tags". For example, the title of this document is:

Calisphere and OAC Technical Framework . Because particular document segments are identifiable by software, sophisticated searching and display becomes possible. For example, when searching, it would be possible to specify that only document headings should be searched. Also, since the document is rendered for display at the moment of request, some display decisions can be made "on-the-fly," such as providing different versions that display better based on the user's operating system and web browser.

Metadata for all objects in the repository -- regardless of format -- are mapped to the Dublin Core element set for generalizability and to support cross-collection discovery.

Collection Guide Search and Delivery in OAC

OAC uses XTF for search and delivery of EAD collection guides and MARC records. Text searches target the full text of the documents.

EAD is an encoding standard for preserving the hierarchy and designating the content of collection guides to archival holdings worldwide. It enables Internet delivery of these collection guides and also ensures their permanence by providing a stable, non-proprietary encoding format, which is maintained by the Society of American Archivists. In technical terms, EAD comprises a Document Type Definition (DTD) for encoding collection guides that is written following the syntactic rules of the SGML and XML markup languages.

OAI-PMH Data Service

Metadata for EAD collection guides and METS digital objects is available for harvesting via the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). For more information, see our OAI-PMH Data Service documentation.